GBIF's comprehensive guide to understanding and creating Darwin Core Archives (DwC-A), the standard exchange format for biodiversity data. Explains the star schema architecture: one core file (Occurrence, Event, or Taxon) connected to multiple extension files through a shared identifier. Details the meta.xml descriptor file that defines file structure, field mapping, and relationships between core and extensions. Covers the eml.xml metadata file for dataset documentation. Discusses when to use Event Core (recommended for freshwater monitoring with multiple measurements per sampling event), Occurrence Core, or Taxon Core. Shows how the GBIF IPT automatically generates DwC-A packages from mapped source data. Essential for understanding the packaging format used by GBIF, FBIS, and other biodiversity data networks.